The roughriders prefer a dusty brown and dun color scheme, but adapt appropriate camouflage when necessary.  -Per FM: Mercenaries, pg 59.

Though using appropriate camouflage in combat, for parades the Roughriders use a midnight blue with smoke highlights color scheme. –Per Mercenaries Supplemental, page 37.

Other references:
Pillager, FM: Mercenaries (plate 13)
Cestus, Mercenaries Supplemental (color plates)
Atlas, CM: Mercenaries (p 109)


Insignia:

Circa 3059, the regimental insignia, displayed on a ‘Mech’s front torso, a fighter’s fuselage or the side of a vehicle, is a fanged and horned skull on a dun-colored shield.  Per FM: Mercenaries, pg 59.