Like the answers below neutral colors are good for older ladies with grey or salt and pepper hair. Especially nutmeg browns, beige, eggshell, yellows colors. Warm and deep colors are also good such as burgundy, burnt sienna, Cool colors are also great such as teal, violet, blues, and greens.
Basically what I am saying is that all colors are essentially good for grey or salt and pepper hair. Color is your friend!!! Though try not to get colors that wash out your skin or are too matchy for your hair color (such as grey hair and grey clothes will make you look like the wind) :)