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