How can clay be colored?
Clay is not naturally available in many colors and therefore to make your hardened shape attractive you can color it in a variety of colors by using pigments or body stains.
Clay can be colored either before modeling or after it.
If you are making your own clay you can add food colors or acrylic / watercolor paints with glue or water when you are molding the clay. By using primary colors and mixing them in different quantities you can get the desired color.
If you color the clay after you have modeled it, it is like you are painting on a canvas. Under this coloring technique wait until the clay has properly dried and then color it with acrylic or oil paints. After the first coat of paint dries, apply the second coat to give it finishing and then lastly apply a thin layer of clear nail polish.