I claim the ornamental design for a set of straps for flip flops, as shown and described.
FIG. 1 is a perspective view of a set of straps for flip flops, 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 showing sandals in the figures are included for the purpose of illustrating the invention in use, and form no part of the claimed design.