>>49839483
I personally haven't heard of that, though here's what I know:
Mikos wear red and white.
Trainee priests wear green.
Younger priests of the lowest rank wear blue.
Dark blue is worn at shinto funerals.
Senior priests wear purple with a purple crest.
The highest ranked priests wear purple with a white crest.
It seems that Sanae is being shown as a young priestess, and I wonder if that's intentional on ZUN's part.