Hi, Christian...
This site
www.luftarchiv.de is very good for information. Admittedly, it is in German, but if you select the following options, you'll see both a 'standard I/D colours' grid, then a photo of an He111, then a 'Transportgeschwader' grid.
Select:
Luftfahrtindustrie; Motorflugzeuge - 1939-1945, then scroll down about half way. Even if you don't understand German, the grids are colour-coded and easy enough to follow.
Regards...
Paul