You could knit strips and seam the strips together when all the strips are made. It'd be like seaming several scarves together.
For example, you could make five 7"x35" "scarves" and seam them together to make a 35"x35" blanket. So for one strip, you could CO w/ color B and knit for 5", then change color to Y, knit for 5" ... change back to B for 5" and continue to change back and forth.
Then for strip #2, CO w/ color P and knit for 5", change to G and knit for 5", then continue changing until the strip is 35" (or as long/short as you want it).
Once you finish as many strips as you want, then seam them together. I think Amy has a video on seaming too.
I hope that helps!