The GrADS Default colors

Col#  Description   Sample    R   G   B 

0 background 0 0 0 (black by default)
1 foreground 255 255 255 (white by default)
2 red 240 0 0
3 green 0 220 0
4 dark blue 31 61 250
5 light blue 0 199 199
6 magenta 220 0 99
7 yellow 230 220 51
8 orange 240 130 41
9 purple 161 0 199
10 yellow/green 161 230 51
11 medium blue 0 161 230
12 dark yellow 230 176 46
13 aqua 0 209 140
14 dark purple 110 0 220
15 gray 125 125 125

The GrADS Default Rainbow Sequence

Col#  Description   Sample    R   G   B 

9 purple 161 0 199
14 dark purple 110 0 220
4 dark blue 31 61 250
11 medium blue 0 161 230
5 light blue 0 199 199
13 aqua 0 209 140
3 green 0 220 0
10 yellow/green 161 230 51
7 yellow 230 220 51
12 dark yellow 230 176 46
8 orange 240 130 41
2 red 240 0 0
6 magenta 220 0 99

Disclaimer: The color samples may not be displayed properly.