The Imperial Guard fight over vast areas and terrains and as such require specialised Camouflage Schemes in order to blend into their background. Having desert gear on an ice world for example is just asking for an assault by superior forces. This is especially relevant to tanks when their size would make them an obvious target.
Tank Camo Schemes
Mars Pattern - Ty Finocchiaro
Scrubland Desert Camo - David Robinson
Chemical Wastes - Jason Foley
Ion Storm Pattern Buyaka - Jason Buyaki
Snow Camo - Rob Hawkins
Jungle/Forest Camo - Rick Smith
Fire Wastes - Jason Buyaki
375th Death Korp of Krieg Plasma Storm Pattern - Jason Buyaki