The parade colors of the Guards are a mix of white and purple paneling, with black accents.
Per FM:Free Worlds League, page 44.
Achileus Battle Armor, CB: Miniatures Rules (p 21)
The insignia of the Free Worlds Guards is a yellow, red and black shield held aloft by silver wings. All Guards units carry this marking, on the right leg of 'Mechs, the tail plane of aerospace craft or the forward glacis of vehicles. The insignia of the First Free Worlds Guards shows a charging Orion BattleMech, its weapons raised and firing. Per FM: Free Worlds League, pages 43 and 44.