laxman,
if the Stug crewmember represents a member of the Heer (army) after/ during 44 it should be painted in Feldgrua. you should not paint it in SS Pea Pattern(44 dot camo). many Heer stug crewmembers also wore private purchased uniforms such as stug Bluses done in splinter B (heer) camo made from old Heer zeltbahns, although this was not a issued item it was common. i have also seen one that was all black leather , this was also privatly made and not a issue item and very rare.
all stug uniforms wether Waffen SS,Heer and Luftwaffe were issued in Feldgrua, never Panzer black. becuase Stugs and there crew members were not considerd part of the Panzer arm. they were actually considerd artillery.