I claim the ornamental design for a visor cover for headwear cap, as shown and described.
FIG. 1 is a top plan view of a visor cover for headwear cap;
FIG. 2 is a left side elevation view of the visor cover for headwear cap;
FIG. 3 is a right side elevation view of the visor cover for headwear cap;
FIG. 4 is a front elevation view of the visor cover for headwear cap;
FIG. 5 is a rear elevation view of the visor cover for headwear cap;
FIG. 6 is a bottom plan view of the visor cover for headwear cap;
FIG. 7 is a perspective view of the visor cover for headwear cap; and,
FIG. 8 is a perspective view of the visor cover for headwear cap.
The ball cap illustrated by broken lines in FIG. 8 represents environmental structure, and assists in illustrating how the claimed design may appear when used in conjunction with another piece of headwear, but forms no part of the claimed design.