All Sword of Light regiments use a flat red paint scheme in the field and on parade.

Per FM:Draconis Combine, page 83.

Other references:
Dragon, FM: Draconis Combine (plate 7)
Wasp, Camo Specs (p 6)
Dragon, Classic Battletech Box Set (back cover)
Dragon, CM: Kurita (p 26)
Dragon, CM: Kurita (p 29)
Guillotine, Dragon, Quickdraw, Panther, CM: Kurita (p 90)
Wasp, CM: Kurita (p 95)
Dragon, Spider, Jenner, Marauder, Hunchback, Panther, Cyclops, CM: Kurita (p 106)


Insignia:

The crest of House Kurita is painted on each BattleMech’s left shoulder, with the color of the dragon changing for each regiment. The symbol of the regimental division, a blazing sword, appears on every ‘Mech’s back and on the front of the right leg. Its symbol is the Kurita crest with a golden dragon. Per FM: Draconis Combine, pages 83 and 86.