Long hair after 40 doesn’t automatically make you look older, but since hair thins as you age, pump up the volume with layers and movement around the face. “Poker-straight styles are too harsh,” says stylist Byron Williams, who has worked with Demi Moore. Los Angeles stylist Chris McMillan advises parting hair on the side. “It will open up your entire face and give you a fresh, wide-awake look,” he says.
I guess it depends on every women. Some still looks good with a straight long hair after 40′s.