The ornamental design for a cap for an aerosol can, as shown and described.
FIG. 1 is a perspective of a cap for an aerosol can, a tamper-evident band and a portion of a top of the cap being shown in broken lines and forming no part of the claimed invention;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a right elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a left elevational view thereof; and,
FIG. 7 is a bottom plan view thereof, a bottom portion and internal ribs being shown in broken lines and forming no part of the claimed invention.
The broken lines in the drawings indicate environmental structure which forms no part of the claimed design.