After their participation in Operation Guerrero in 3057, the Bandits employed a green with gold striping color scheme. Before then, their equipment was painted charcoal and magenta.
Per FM: Merc (revised), page 101, and CSO. Updated 3/2/24
Other references:
Hunchback, Camo Specs (p 16)
Hunchback, CM: Mercenaries (p 111)
Their famous, three-circles insignia is painted on the upper left legs and right shoulders of all Bandit ‘Mechs. Per FM:Mercenaries Revised, page 101.