The Nightriders

The Nightriders paint their ‘Mechs and vehicles ash gray with silver trim.

Per FM:Capellan Confederation, page 87.

Other references:
Goblin ISV, Classic Battletech Master Rules Revised Edition (plate 5)


Insignia:

They all display the Confederation crest in addition to the Cavalry emblem, an armored knight with a red plume in his helm rising from a green triangular field. Each regiment except for the Wild Ones also displays a regimental insignia, usually on the back of the shoulder or the upper leg.

The regimental insignia is a fire-breathing, mechanical black horse galloping over a green field.

Per FM:Capellan Confederation, pages 86 and 87.