There's a couple of great books out there (websites too, I'd imagine) that have real colour WW2 photos - not colourized B&W images, but actual colour ones.
Modern colour film was a late 1930s invention, but expensive and rare, obviously. The best of it took very, very good colour images, though, and lasted.
The most striking from one book was a tank on exercises somewhere in England, posed with about five different colours of signal smoke around it!