The Keystone Yeomanry
The Marik Militias use a color scheme first seen in 2620--purple with red accents on the right side and blue on the left.
Per FM:Free Worlds Legue, page 58.
Each 'Mech displays the Marik Militia crest - a stylized Marik Eagle on a red and blue background - on its left arm or weapons pod. The insignia of the 6th Militia shows an archer holding a drawn longbow. Per FM: Free Worlds League, pages 53 and 58.