Yes the yellow color comes from two sources. First the panel is alum and was alodined and then the yellow 3M Adhesive was used to secure the plastic overlay.
You are correct that you can remove the alum overlay on your panel, just make sure to keep track of where the screws come out of, and support the instruments. Be sure to prep the alum (wash, acid etch W01 acid, rinse, alodine, then ready for powder.