What were the meanings of the non-black clerical shirts post Vatican II?

I was listening to a recent Pints with Aquinas (about 25 minutes in) https://open.spotify.com/episode/4GTsBlLybMDqQCxdYltRO4?si=fd22facaad8040a5 the priest being interviewed was talking about different color clerical shirts having some hidden meaning. Is there a list of secret meanings behind this clerical garb? Gray, white, etc... were there other colors that were used in the 1960's and 1970's?