One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6)(7,9)(8,10)(11,12)(13,14)(15,20)(16,22)(17,23)(18,21)(19,24)(25,28)(26,27) involution — undirected(1,2)(3,4)(5,6)(7,11)(8,10)(9,12)(13,15,19,25)(14,20,24,28)(16,17,26,18)(21,22,23,27)(5,7,8,12)(6,9,10,11)(14,21)(16,26)(17,18)(20,22)(23,24)(27,28)(2,4)(7,12)(9,11)(13,16)(14,22)(15,17)(18,25)(19,26)(20,23)(21,28)(24,27) involution — undirected(6,10)(9,11)(13,17,19,18)(14,23,24,21)(15,16,25,26)(20,22,28,27)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.