Here are some ideas for coloring your soaps with natural/organic colors.
Add a couple teaspoons of the herb per pound of soap:
Tumeric: make a mustard yellow soap
Red Sandalwood powder: Makes a grape/purple soap
Rubbed Sage: makes a sage green soap
Calendula: makes a pastel yellow soap

Using herbs gets so-so results. They can look very pretty to start and then within a few weeks the color begins to mute and starts to fade. Commercial dyes like our oil based powdered colorants are the most consistent and reliable way to go, but sometimes you might want to just use what nature has to offer.

Feel free to add more herbs that you've tried and received good results with for color.