The iconic color for the Free Worlds League is purple. The reason is twofold: not only is the Free Worlds League crest dominated by the purple Marik eagle, but one of the most significant portions of the League military is the Marik Militia, which uses purple as it primary color (with red accents on the right and blue accents on the left). Though purple is iconic for House Marik, green and white are used almost as frequently.
Iconic Paint Colors:
Apple Barrel Petunia Purple, Citadel Xereus Purple, VMC Violet, VGC Hexed Lichen, Reaper Imperial Purple.
Other Primary Paint Colors:
Apple Barrel Forest Green, Apple Barrel Spring Green, Citadel Warboss Green, Citadel Skarsnik Green, VGC Goblin Green, VGC Scorpion Green, VMC Intermediate Green, VMC Olive Green.
Purple can be highlighted by mixing white into your base color, or—depending on the shade of purple—it can be highlighted by mixing in pink or light blue. A targeted black wash will work with purple, but a blue-black or dark blue targeted wash looks even better.