The ornamental design for a set of keybuttons for a keyboard, as shown and described.
FIG. 1 is a perspective view of a set of key buttons for a keyboard showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing of the remainder of the keyboard is included for the purpose of illustrating unclaimed portions of the article and forms no part of the claimed design.