If you want to use dried herbs and have them retain something close to their original color and scent, you could try the HP method and stir them in at the end of the cook. Then the lye will be neutralized and less likely to affect the herbs.
Almost all oil infusions or teas I've made with green botanicals have resulted in brown soap. Nettle and comfrey-infused oils will produce green soaps but a more muted green which will fade towards olive green over time. Botanicals are also more sensitive to sun exposure so keep naturally colored soaps in a dark place.
Calendula stays yellow and alkanet, yellow dock, and madder are good for pinks, reds, and purples. The shade is often unpredictable, but that's half the fun.