One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(6,10)(7,8)(11,12)(13,14)(15,18)(16,19)(17,20)(21,25)(22,26)(23,27)(24,28) involution — undirected(5,6)(7,10)(8,12)(9,11)(13,15,17,22)(14,18,20,26)(16,23,24,21)(19,27,28,25)(2,4)(13,16,17,24)(14,19,20,28)(15,21,22,23)(18,25,26,27)(14,20)(18,26)(19,28)(25,27) involution — undirected(5,7,9,8)(6,10,11,12)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.