I've just been sent a scrambled octagonal prism, that is a 3x3x3 cube with four edges cut off at 45 degrees and a different colour stickers on each of these cut-off faces.

I'm trying to solve it as a normal 3x3x3 cube, but this doesn't work because I don't know which 45-degree face is equivalent to which edge. Does anyone either know which edge is which, or any way of working this out?

The octagonal ends of the prism are white and red, the other four square centres are dark green, blue, orange, yellow clockwise when looking from the white end. The 45-degree faces are pink, purple, turquoise and light green. I've found a few pictures of octagonal prism "cubes", but none of them have the same colours as mine. I've seen algorithms for solving parity errors, but nothing about finding the order of the sides.

Any help would be appreciated.