Mix together all the ingredients, except the food coloring, in a medium saucepan.
Cook over medium low heat, stirring with a wooden spoon. Continue to stir until the mixture is very thick, sticks to the spoon, and hard to stir. This will all take about 10-15 minutes and will become a bit of a workout!
Feel the dough. It should not feel wet, but should easy get imprints in it if you squeeze it or press into it.
Transfer the dough to a piece of wax paper for 5 minutes.
Divide up into sections (I did 8 colours so I split it into 8). Add a section to a bowl and add a bit of food colouring. I suggest starting with the lightest colours (ie. yellow) so you don't have to keep washing the bowl out. Kneed the colour into the dough.