Mix all ingredients except for food coloring in a large pot.Cook and stir on low heat for 5 minutes or until mixture forms a ball.Cool completely before adding color. Roll out playdough and divide it into 4 equal pieces (or as many pieces as you have colors). Place 2-3 drops of food coloring onto each piece of playdough, kneading it through until you reach your desired color. Wear plastic gloves if you don't want food coloring to stain your hands.Store playdough in a sealable plastic bag.