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