These are color-coded by size. Don't think they were made in other colors.
Auer does make them in many different colors, but their system is multiples of 52mm, not 49mm like the Festool bins. And that is still different from Allit, which uses 54mm boxes [sad]. Sortimo seems to have the same as Auer though, multiples of 52x52 and 63mm height.
The Festool bins also changed size just so slightly when they went from Systainer Classic to T-Loc. I think the bottom end also changed.
For the new Sys3 organizer there are gray boxes in different sizes, but they aren't compatible with the Sys Box.
Personally I found the Systainer not strong enough to fill it to the brim with screws, so I have the metal Allit boxes for that. I have four (nearly) full boxes, and still lacking space ever since I bought a bunch of stainless screws.