I need to see the whole house. What was the reason for the dormer ?

You want to match the blue siding?

Yes @Indecisiveness

@Patricia Colwell Consulting

I'm not sure why the contractor removed the dormer siding.

The roofer might have needed to redo the flashing At the dormer walls.

Id have him put in cedar clapboard then you can match the paint color to the body of the house.

Use hardi siding and paint it to match the aluminum on the rest of the house. At least in my area the siding on dormers always matched the main house

For the single window dormer shingles would allow the corners to be wrapped but that doesn't look possible for the triple window dormer. An alternative would be to use Hardie Artisan lap siding and miter the corners.