Hi J.,
I'm forty and have been flirting with those wiry, silvery strands in my hair for a while now. I gave up on coloring when I was 33 or so and haven't regretted it. Getting a regular haircut from a trustworthy stylist helps, and since I'm a preschool teacher, I can keep my style of clothing low-key and fun too: jeans, a couple favorite hoodies/sweaters, and some pretty classic-cut tops. (I'm a big fan of simple, flattering crew-neck type shirts.) I keep my makeup and jewelry pretty low-key too: just some powder on my face, (heavy makeup makes one look older) and some simple earrings and a couple rings.
I always believe that one will look best in what one *feels good* in, whether it's a fancy top and skirt, or jeans and a go-to sweater. Wearing clothes one dislikes usually makes us feel--and look--frumpier.
Oh, and as much as I'm mostly annoyed by style magazines, do take a look at how some of them offer different styles for different ages. I know I'm not rocking the miniskirts or peg-legged jeans any more. Finding clothes that feel right for one's level of personal maturity, and which don't scream "Hey, look at me! I've still got a rocking body! I look young and hip! Just like my daughter!" is helpful, too.