All Ryuken units paint their BattleMechs charcoal gray. Ryuken-san warriors do not accent their vehicles with any color.

Per FM:Draconis Combine, page 128.

Other references:
Panther, CM: Kurita (p 104)


Insignia:

The Ryuken apply the Kurita dragon crest to their BattleMechs on the left leg just above the knee and near the exhaust ports of fighters. The Ryuken insignia is a dragon curling around a Katana sword, both drawn with rich detail. Ryuken-san warriors display the Kuritan and Ryuken crests and the Reyuken-san regimental insignia, a narrow gold line that sketches out an angular dragon’s head across each ‘Mech’s torso. Per FM: Draconis Combine, pages 126 and 128.