I don't know that I entirely agree that unless they are willing to become invisible women are seen as trying to look young. Nor that "dressing your age" which is a rather unpleasant phrase is all about trying to make women look more invisible.
I do know that some women feel that they become invisible, but I also know lots of women who feel as they get into middle age or beyond that they are taken more seriously. I'm not sure what the difference is between these groups of people, but it seems like it can go both ways from my perspective. For myself, I probably fall more into the latter group, I have more responsibility, you could say more power in my job, my position is stable in a way it wasn't before. There are women who find the opposite, but also men too who as they age find things like their job status becomes more precarious.
I do think there is something to be said for accepting things such as, your face will age, your body will change. The clothing stuff from my perspective is mainly about that - about not trying to look younger because that is somehow better. There are older women who are very fashionable and absolutely not invisible. And they can carry off things that would not look good or right on younger women. Some of it is that young people's clothing tends to be cheaper and more fad based.