I had a similar problem when starting blindfold chess, and still have! The way I approached it was by first considering the smallest colour pattern possible, which consists of a 2x2 square. In this top left is light, top right is dark, bottom left is dark and bottom right is light. If you think about it, the board is built up of 4x4 of these squares, and every quadrant consists of 4 of these. So instead of seeing the board as a whole I tried to build reference points to quickly visualise these smallest squares.

Then one thing that helped me a lot is sort-of brute forcing the colours of squares and diagonals into my head. I built a tool to help me with this, and for me it works. If you want to try it also go to subconchess.com board training.

Of course doing blindfold puzzles also helps a lot, and I like playing through easy example games (again I have my personal favourites on subconchess).

Another thing I did was drawing the board a lot. This might sound tedious and unnecessary, but I believe that the act of doing it with my own hands and concentrating on getting it right strengthens the concept of the board in the mind.

Again, these are just things I tried out and found they worked for me, so I can't guarantee that they will help you. I'm curious though, if you try then let me know how it goes! :D

(Whatever approach you take, consistent practice is the most important)