Set the game to the monitor's native resolution? Why are you playing in non-native?
...I don't know what you mean by distorted and colorless. LCD monitors look best in their native resolution. When you deviate from that, the image quality degrades rapidly the further you get away from native - one reason I still kinda miss CRT screens - but I'm not sure why it would 'distort' the image, unless you're playing in 4:3 on a 16:9 monitor and "stretching" the image to fill the 16:9, perhaps. Altho I'd think most screenshot programs wouldn't record the stretched version but rather the normal given aspect ratio for a screenshot...
I play with the aspect ratio on 16:9 to fit my monitor and the game looks great with the resolution set to 1366x768, but when I take a screenshot in game with the 'PrntScr' key while set to that resolution and not 1280x720, the image is gray, crooked, and parts of it display on the wrong side of the screen. I would upload a picture to show as an example, but I can't figure how. For some reason no converting program I have can read the higher resolution screenshot files and I can't find a single image uploading site that supports the bmp. format either, so I can't provide a link.