I took a look at the features of the Apple IIGS chipset.
Actually can have a better tint than ST version because of the 2^4^3 colors space (like Amiga OCS).
And a scan lines based (16 colors banked) palette selection, that can be easy emulated by Copper (who knows if actually used in this game).
So yes, graphics can be slightly better on GS,
but it's probably difficult to notice the difference if only 16 colors are used