Place your one cup of dry pasta into a resealable bag or container. Add a squirt or two of liquid watercolor or food color (you can even use watered down acrylic paint), seal the bag and shake it up. Use your fingers to smoosh the paint around from the outside of the bag. For color stay noodles, you can add a tablespoon of vinegar or rubbing alcohol. The rubbing alcohol will help the noodles dry more quickly. You do not need to add either this is optional. If I remember I do, if I don't, I do not worry about it.
Spill the damp and now colorful noodles onto a cookie sheet that has been lined with wax or parchment paper until dry. It takes about 15 minutes to dry. Repeat for each color you wish.