When I was attending Church as a kid in the 1950s and early 60s, many women still wore mantillas (the Spanish word for them, as this was southern California) and the shorter versions, called chapel caps. Almost all of them were either white or black, and I never was told of any distinctions regarding marital status – I just thought it was a matter of choice.
Occasionally, I would see one of those in a different color – pastel blue, pink, yellow, even light green. I never knew if there was any significance as to a reason why – again, I thought it was a matter of choice, like maybe those colors went with the rest of the wardrobe they were wearing that day, i.e., part of a fashion statement.
In those more traditional days, women were expected to cover their heads, while men were required to remove their hats. I would see all kinds and sorts of female head coverings, especially at Easter. Huge, broad-brimmed hats with artificial flowers on them, ribbons and bows, etc. It was part of dressing up for Church.
I still, very rarely, see lacy head coverings today – mantillas, chapel caps or scarves, and I rarely see hats in general. Women have gotten away from wearing head coverings in church, although men still, for the most part, remove their hats.