One option would be similar to a pleated lamp shade or pleated dress. Both of these have a surface that is folded, but has an opening in the center (for light, or legs)
Imagine a flat circular sheet, with a hole in the center. When it is time to fold up the sail, the covers for the compartment where the sail will be stored are opened. Once these covers are verified open (and the interior checked) lines carefully pull on the sail, so it starts forming the ridges and valleys. The sail as a whole is being slowly pulled 'upward' past the engine nozzle, and inwards to the hull of the ship. As the sail gets closer to the hull of the ship, the pleats in the sail get more pronounced, and the sail goes from being a flat plane to being more of a horizontal tube. You will likely have to fold the sail 'length-wise' so the radius of the sail is short enough to fit in the compartment.
By pleating, I mean something like this (but imagine a hole in the center, instead of the point):
https://www.mdpi.com/symmetry/symmetry-11-01101/article_deploy/html/images/symmetry-11-01101-g004-550.jpgOr for an idea of where the material is wrapped around, you might go with this (page 17, row 'e'):
https://pdfs.semanticscholar.org/e284/c945c73d34137a6c1eaf63931e078cb8e4af.pdfOr like this:
https://www.youtube.com/watch?v=ThwuT3_AG6wTimes to watch are: 0:10, 6:18, 15:45,