First, attached is a super easy cheat way. You can draw by hand, and replace the blocks with coloured ones.
This is a quick solution, but not great for highly complicated images that you might want to load.
A better solution would be to load the values into an array, then build the image on the fly. Then you can check the array for the correct value to colour with. That way you can load via files/JSON etc.
This however might give you some thoughts to mull.