The ornamental design for a cover of an electronicdevice with surface pattern, as shown and described.
FIG. 1 is a perspective view of a cover of an electronic device with surface pattern showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof; and,
FIG. 4 is an enlarged view thereof, of circled portion 4 in FIG. 2.
In FIGS. 1-3, the evenly segmented broken lines indicate portions of the cover of an electronic device with surface pattern that form no part of the claimed design. In FIGS. 2 and 4, the alternating long-dash short-dash type broken lines represent the boundary of the portion of the electronic device with surface pattern that is shown on an enlarged scale in FIG. 4.