We love using salt dough for our craft projects, but it's even better when the dough is coloured (and it saves having to paint it). Here is the simple recipe that we use to make coloured salt dough.
We use the basic recipe below but to add colour to the salt dough we mix paint into the water before mixing it with the other ingredients. To make a bold colour you need to mix about 1/2 water 1/2 paint. I have successfully used both acrylic paint and poster paint (whatever we have in the house in the colour I want!) Just watch that the colour doesn't transfer to your hands as you knead the dough!
You can also use food colouring but I have found that the colours tend to be paler (which is great if that's what you are after!) Alternatively if you want natural dough you can colour your dough by adding spices to your mixture instead of paint or food colouring.
Once you have made your creations leave them to dry out. You can leave the salt dough to dry in a warm room for a couple of days or put it in the oven at a low temperature for a couple of hours (I turn my oven to 150 degrees). Just be careful not to brown them in the oven if you want to keep the colour!
The colours do fade a little as the salt dough dries but if you varnish your creations most of the colour comes back. We use Mod Podge all in one sealer glue and finish (UK affiliate link) (US affiliate link) to varnish and preserve our creations.