Facebook is certainly a good option for this. But what kind of women above 40 are you looking to target? Are they stay-at-home moms? Professional women? Affluent? Savings-centric? This will make some difference in how you'll want to target both your advertising and your messaging.

I'm guessing that you are a local salon rather than a national network (but correct me if I'm wrong). In addition to Facebook, it's worth looking into your metro area's popular digital content -- newsletters, local blogs that are well-read among that demographic, etc.

I'm happy to take a call about this if you're interested in hearing more about how to create a blend of paid and earned media.