Those are the figures we have available. The big guy in the back is the Kree Scout's figure. The one in black is a Private (which are black and purple from what I've seen), green is Captain, blue is Colonel.
We could repaint them into some sort of generic color, I suppose, if we want to reuse the same sculpt four times. But I feel like putting that much effort into a character that doesn't even "really" exist is odd - though I wouldn't be the one designing or painting, so, that's not really up to me.
For reference, here's the color key for Kree:
Black/Purple - Private
Brown - Lieutenant
Green - Captain
Orange - Major
Blue - Colonel
Pink- General