I haven't used FD&C colors, dyes or lakes, not so much because I have any real issues with them, but more because I like the interesting (and often unpredictable) colors that I get from using earthy things like herbs, spices, and minerals.
For the most part, I do not give suggestions on usage rates. These will vary, depending on the color you're wanting. You may want to google a bit, for precautions on some natural colorants, before using them. For example, cinnamon has been known to cause allergic reactions in some people (although I have never experienced this).
Some of the natural colorants I've used, the soapmaking method I used, and the resulting color.
Activated Charcoal- I used this in CP soap, and gelled. Creates BLACK soap. Can be used in smaller quantities to make gray soap.
Alkanet Root-- used in CP Soap, no gel. The color I got was a medium dove gray. Although, at initial pour, it was a BEAUTIFUL baby blue. Blue's are often pH sensitive, the high pH of the batter is most likely the cause of the color morphing.
Calendula-- used in CP, with gel. Produces a harvest gold, earthy gold, gorgeous color. In fact, bought mine from mountain rose herbs, and the cured soap is identical in color to the dried calendula powder.
Carrot Juice- used in CP with gel. used in place of water, or in partial place of water. Awesome orange. SImilar to pumpkin pie color, but not as intense.
Cinnamon- used in CP with gel. Leaves gorgeous little specks of warm brown all throughout the soap.
Cocoa Powder- used in CP with and without gel. Gives a rich, chocolaty brown.
Cucumber-- used in CP with gel, in place of water. Pureed in a food processor. Cured soap will be a pale, yellow/golden color. I have read that the ground peel creates green specks in the soap. It does- but they fade as the soap cures, leaving slightly darker yellow specks in the soap. Not very noticeable though.
Green Tea Leaves- used in CP with gel. These always turn brown. The green color will not stay.
Oatmeal- used in a 35% olive oil soap recipe. Ground it in a food processor. Leaves a warm creamy beige color, with little flecks of cream, white, brown (the same variety of colors you'll see in a bowl of cooked oatmeal!).
Poppyseed-- used in CP with and without gel. Adds lovely, dark gray/black scrubbies for texture, without affecting the color of your soap.
Rosemary Powder-- used in CP with gel. Starts as a nice earthy green, fades to beige with light brown specks (similar to cinnamon's specks- see above), although the color of the soap will be a slightly yellower brown than cinnamon produces. Soft and natural looking.
Spirulina- used in CP, with gel. Depending on amount used, can create a "Christmas Green" at pour. However, the color fades with cure, to a very pale, cucumber-flesh green. I 've used up to 2 T. in a 5# total weight batch.
Turmeric- used in CP, with gel. Gives a golden to orange color. Used in many cultures as an antibacterial agent, but I'm not sure if that quality survives saponification. I use it for it's color.
Feel free to send in suggestions for this list!