Here are some example color selections to choose from or define your own. GraphicsMagick understands color names or hex values (.e.g. white or #ffffff).

Name Color RGB Hex
alicebluealiceblue240, 248, 255#f0f8ff
antiquewhiteantiquewhite250, 235, 215#faebd7
aquaaqua0, 255, 255#00ffff
aquamarineaquamarine127, 255, 212#7fffd4
azureazure240, 255, 255#f0ffff
beigebeige245, 245, 220#f5f5dc
bisquebisque255, 228, 196#ffe4c4
blackblack0, 0, 0#000000
blanchedalmondblanchedalmond255, 235, 205#ffebcd
blueblue0, 0, 255#0000ff
bluevioletblueviolet138, 43, 226#8a2be2
brownbrown165, 42, 42#a52a2a
burlywoodburlywood222, 184, 135#deb887
cadetbluecadetblue95, 158, 160#5f9ea0
chartreusechartreuse127, 255, 0#7fff00
chocolatechocolate210, 105, 30#d2691e
coralcoral255, 127, 80#ff7f50
cornflowerbluecornflowerblue100, 149, 237#6495ed
cornsilkcornsilk255, 248, 220#fff8dc
crimsoncrimson220, 20, 60#dc143c
cyancyan0, 255, 255#00ffff
darkbluedarkblue0, 0, 139#00008b
darkcyandarkcyan0, 139, 139#008b8b
darkgoldenroddarkgoldenrod184, 134, 11#b8860b
darkgraydarkgray169, 169, 169#a9a9a9
darkgreendarkgreen0, 100, 0#006400
darkgreydarkgrey169, 169, 169#a9a9a9
darkkhakidarkkhaki189, 183, 107#bdb76b
darkmagentadarkmagenta139, 0, 139#8b008b
darkolivegreendarkolivegreen85, 107, 47#556b2f
darkorangedarkorange255, 140, 0#ff8c00
darkorchiddarkorchid153, 50, 204#9932cc
darkreddarkred139, 0, 0#8b0000
darksalmondarksalmon233, 150, 122#e9967a
darkseagreendarkseagreen143, 188, 143#8fbc8f
darkslatebluedarkslateblue72, 61, 139#483d8b
darkslategraydarkslategray47, 79, 79#2f4f4f
darkslategreydarkslategrey47, 79, 79#2f4f4f
darkturquoisedarkturquoise0, 206, 209#00ced1
darkvioletdarkviolet148, 0, 211#9400d3
deeppinkdeeppink255, 20, 147#ff1493
deepskybluedeepskyblue0, 191, 255#00bfff
dimgraydimgray105, 105, 105#696969
dimgreydimgrey105, 105, 105#696969
dodgerbluedodgerblue30, 144, 255#1e90ff
firebrickfirebrick178, 34, 34#b22222
floralwhitefloralwhite255, 250, 240#fffaf0
forestgreenforestgreen34, 139, 34#228b22
fractalfractal128, 128, 128#808080
fuchsiafuchsia255, 0, 255#ff00ff
gainsborogainsboro220, 220, 220#dcdcdc
ghostwhiteghostwhite248, 248, 255#f8f8ff
goldgold255, 215, 0#ffd700
goldenrodgoldenrod218, 165, 32#daa520
gray0gray00, 0, 0#000000
gray1gray13, 3, 3#030303
gray2gray25, 5, 5#050505
gray3gray38, 8, 8#080808
gray4gray410, 10, 10#0a0a0a
gray5gray513, 13, 13#0d0d0d
gray6gray615, 15, 15#0f0f0f
gray7gray718, 18, 18#121212
gray8gray820, 20, 20#141414
gray9gray923, 23, 23#171717
gray10gray1026, 26, 26#1a1a1a
gray11gray1128, 28, 28#1c1c1c
gray12gray1231, 31, 31#1f1f1f
gray13gray1333, 33, 33#212121
gray14gray1436, 36, 36#242424
gray15gray1538, 38, 38#262626
gray16gray1641, 41, 41#292929
gray17gray1743, 43, 43#2b2b2b
gray18gray1846, 46, 46#2e2e2e
gray19gray1948, 48, 48#303030
gray20gray2051, 51, 51#333333
gray21gray2154, 54, 54#363636
gray22gray2256, 56, 56#383838
gray23gray2359, 59, 59#3b3b3b
gray24gray2461, 61, 61#3d3d3d
gray25gray2564, 64, 64#404040
gray26gray2666, 66, 66#424242
gray27gray2769, 69, 69#454545
gray28gray2871, 71, 71#474747
gray29gray2974, 74, 74#4a4a4a
gray30gray3077, 77, 77#4d4d4d
gray31gray3179, 79, 79#4f4f4f
gray32gray3282, 82, 82#525252
gray33gray3384, 84, 84#545454
gray34gray3487, 87, 87#575757
gray35gray3589, 89, 89#595959
gray36gray3692, 92, 92#5c5c5c
gray37gray3794, 94, 94#5e5e5e
gray38gray3897, 97, 97#616161
gray39gray3999, 99, 99#636363
gray40gray40102, 102, 102#666666
gray41gray41105, 105, 105#696969
gray42gray42107, 107, 107#6b6b6b
gray43gray43110, 110, 110#6e6e6e
gray44gray44112, 112, 112#707070
gray45gray45115, 115, 115#737373
gray46gray46117, 117, 117#757575
gray47gray47120, 120, 120#787878
gray48gray48122, 122, 122#7a7a7a
gray49gray49125, 125, 125#7d7d7d
gray50gray50127, 127, 127#7f7f7f
gray51gray51130, 130, 130#828282
gray52gray52133, 133, 133#858585
gray53gray53135, 135, 135#878787
gray54gray54138, 138, 138#8a8a8a
gray55gray55140, 140, 140#8c8c8c
gray56gray56143, 143, 143#8f8f8f
gray57gray57145, 145, 145#919191
gray58gray58148, 148, 148#949494
gray59gray59150, 150, 150#969696
gray60gray60153, 153, 153#999999
gray61gray61156, 156, 156#9c9c9c
gray62gray62158, 158, 158#9e9e9e
gray63gray63161, 161, 161#a1a1a1
gray64gray64163, 163, 163#a3a3a3
gray65gray65166, 166, 166#a6a6a6
gray66gray66168, 168, 168#a8a8a8
gray67gray67171, 171, 171#ababab
gray68gray68173, 173, 173#adadad
gray69gray69176, 176, 176#b0b0b0
gray70gray70179, 179, 179#b3b3b3
gray71gray71181, 181, 181#b5b5b5
gray72gray72184, 184, 184#b8b8b8
gray73gray73186, 186, 186#bababa
gray74gray74189, 189, 189#bdbdbd
gray75gray75191, 191, 191#bfbfbf
gray76gray76194, 194, 194#c2c2c2
gray77gray77196, 196, 196#c4c4c4
gray78gray78199, 199, 199#c7c7c7
gray79gray79201, 201, 201#c9c9c9
gray80gray80204, 204, 204#cccccc
gray81gray81207, 207, 207#cfcfcf
gray82gray82209, 209, 209#d1d1d1
gray83gray83212, 212, 212#d4d4d4
gray84gray84214, 214, 214#d6d6d6
gray85gray85217, 217, 217#d9d9d9
gray86gray86219, 219, 219#dbdbdb
gray87gray87222, 222, 222#dedede
gray88gray88224, 224, 224#e0e0e0
gray89gray89227, 227, 227#e3e3e3
gray90gray90229, 229, 229#e5e5e5
gray91gray91232, 232, 232#e8e8e8
gray92gray92235, 235, 235#ebebeb
gray93gray93237, 237, 237#ededed
gray94gray94240, 240, 240#f0f0f0
gray95gray95242, 242, 242#f2f2f2
gray96gray96245, 245, 245#f5f5f5
gray97gray97247, 247, 247#f7f7f7
gray98gray98250, 250, 250#fafafa
gray99gray99252, 252, 252#fcfcfc
gray100gray100255, 255, 255#ffffff
graygray126, 126, 126#7e7e7e
greengreen0, 128, 0#008000
greenyellowgreenyellow173, 255, 47#adff2f
greygrey128, 128, 128#808080
honeydewhoneydew240, 255, 240#f0fff0
hotpinkhotpink255, 105, 180#ff69b4
indianredindianred205, 92, 92#cd5c5c
indigoindigo75, 0, 130#4b0082
ivoryivory255, 255, 240#fffff0
khakikhaki240, 230, 140#f0e68c
lavenderlavender230, 230, 250#e6e6fa
lavenderblushlavenderblush255, 240, 245#fff0f5
lawngreenlawngreen124, 252, 0#7cfc00
lemonchiffonlemonchiffon255, 250, 205#fffacd
lightbluelightblue173, 216, 230#add8e6
lightcorallightcoral240, 128, 128#f08080
lightcyanlightcyan224, 255, 255#e0ffff
lightgoldenrodyellowlightgoldenrodyellow250, 250, 210#fafad2
lightgraylightgray211, 211, 211#d3d3d3
lightgreenlightgreen144, 238, 144#90ee90
lightgreylightgrey211, 211, 211#d3d3d3
lightpinklightpink255, 182, 193#ffb6c1
lightsalmonlightsalmon255, 160, 122#ffa07a
lightseagreenlightseagreen32, 178, 170#20b2aa
lightskybluelightskyblue135, 206, 250#87cefa
lightslategraylightslategray119, 136, 153#778899
lightslategreylightslategrey119, 136, 153#778899
lightsteelbluelightsteelblue176, 196, 222#b0c4de
lightyellowlightyellow255, 255, 224#ffffe0
limelime0, 255, 0#00ff00
limegreenlimegreen50, 205, 50#32cd32
linenlinen250, 240, 230#faf0e6
magentamagenta255, 0, 255#ff00ff
maroonmaroon128, 0, 0#800000
mediumaquamarinemediumaquamarine102, 205, 170#66cdaa
mediumbluemediumblue0, 0, 205#0000cd
mediumorchidmediumorchid186, 85, 211#ba55d3
mediumpurplemediumpurple147, 112, 219#9370db
mediumseagreenmediumseagreen60, 179, 113#3cb371
mediumslatebluemediumslateblue123, 104, 238#7b68ee
mediumspringgreenmediumspringgreen0, 250, 154#00fa9a
mediumturquoisemediumturquoise72, 209, 204#48d1cc
mediumvioletredmediumvioletred199, 21, 133#c71585
midnightbluemidnightblue25, 25, 112#191970
mintcreammintcream245, 255, 250#f5fffa
mistyrosemistyrose255, 228, 225#ffe4e1
moccasinmoccasin255, 228, 181#ffe4b5
navajowhitenavajowhite255, 222, 173#ffdead
navynavy0, 0, 128#000080
nonenone0, 0, 0#000000
oldlaceoldlace253, 245, 230#fdf5e6
oliveolive128, 128, 0#808000
olivedrabolivedrab107, 142, 35#6b8e23
orangeorange255, 165, 0#ffa500
orangeredorangered255, 69, 0#ff4500
orchidorchid218, 112, 214#da70d6
palegoldenrodpalegoldenrod238, 232, 170#eee8aa
palegreenpalegreen152, 251, 152#98fb98
paleturquoisepaleturquoise175, 238, 238#afeeee
palevioletredpalevioletred219, 112, 147#db7093
papayawhippapayawhip255, 239, 213#ffefd5
peachpuffpeachpuff255, 218, 185#ffdab9
peruperu205, 133, 63#cd853f
pinkpink255, 192, 203#ffc0cb
plumplum221, 160, 221#dda0dd
powderbluepowderblue176, 224, 230#b0e0e6
purplepurple128, 0, 128#800080
redred255, 0, 0#ff0000
rosybrownrosybrown188, 143, 143#bc8f8f
royalblueroyalblue65, 105, 225#4169e1
saddlebrownsaddlebrown139, 69, 19#8b4513
salmonsalmon250, 128, 114#fa8072
sandybrownsandybrown244, 164, 96#f4a460
seagreenseagreen46, 139, 87#2e8b57
seashellseashell255, 245, 238#fff5ee
siennasienna160, 82, 45#a0522d
silversilver192, 192, 192#c0c0c0
skyblueskyblue135, 206, 235#87ceeb
slateblueslateblue106, 90, 205#6a5acd
slategrayslategray112, 128, 144#708090
slategreyslategrey112, 128, 144#708090
snowsnow255, 250, 250#fffafa
springgreenspringgreen0, 255, 127#00ff7f
steelbluesteelblue70, 130, 180#4682b4
tantan210, 180, 140#d2b48c
tealteal0, 128, 128#008080
thistlethistle216, 191, 216#d8bfd8
tomatotomato255, 99, 71#ff6347
turquoiseturquoise64, 224, 208#40e0d0
violetviolet238, 130, 238#ee82ee
wheatwheat245, 222, 179#f5deb3
whitewhite255, 255, 255#ffffff
whitesmokewhitesmoke245, 245, 245#f5f5f5
yellowyellow255, 255, 0#ffff00
yellowgreenyellowgreen154, 205, 50#9acd32