I have found that if you play with many variegated yarns you can find the sweet number of stitches to make them separate into their individual colours. This is a Patons Classic Wool variegated yarn. To get this effect, you have to play a bit. Cast on the number of stitches you would normally do for your hat. On your second round, you will see how close or far the colours are from lining up on top of each other. If they are only one or two stitches out, back up a bit and either increase or decrease a couple of stitches before the beginning of the second round. If they are way out, you may have to start over again.
As I was knitting, I periodically had to adjust by increasing or decreasing stitches here and there to keep the colours lined up. I am not sure how successful any of these hats are but as you can see I did three before I gave up.