The best thing I can think of is to find the corners with one colour on them, say black. Then look which colour is missing,
If it was black replacing white and the rest was as a standard cube, you'd find black corners with red & blue, blue & orange, orange & green, and green & red.
Yellow would be missing, so it must be opposite black. You could also say as you had black with red & blue, and red & green, green and blue must also be opposite. This would leave the last 2 colours (orange and red) being opposite.
After that, looking at one corner should help you place the rest. So clockwise, it'd be black on top, then blue then red.
This is only true if your cube has black instead of white on a standard cube layout. If your layout is different, then you'll have to use this method to work it all out. I hope it helps.
Please take off topic discussion off this forum. Thanks.