[TheLazySloth]

SetPlayerColor(playerid, Color);

Colors..
#define White 0xFFFFFFFF
#define Black 0x000000FF
#define Grey 0x5C5C5CFF
#define Brown 0x430000FF
#define Red 0xFF0000FF
#define Orange 0xFF9900FF
#define Yellow 0xFFFF00FF
#define Green 0x00CC00FF
#define Blue 0x0033CCFF
#define Purple 0x660099FF

http://www.colorpicker.com/
To choose a color just find a good shade/hex then define it #define Color 0x//paste here and add FF at the end.