The ornamental design for a shower armdiverter with handheld shower head holder, as shown and described.
FIG. 1 is a perspective view of a shower arm diverter with handheld shower head holder showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines throughout the drawing figures depict portions of the shower arm diverter with handheld shower head holder that form no part of the claimed design.