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)(15,22)(16,20)(17,21)(18,23)(19,27)(24,25)(26,28) involution — undirected(2,4)(6,9)(10,12)(13,15,18,16)(14,20,23,22)(17,25,26,19)(21,27,28,24)(5,7,8,11)(6,10,9,12)(13,16,19,17,18,15,25,26)(14,21,24,20,23,28,27,22)(1,2,3,4)(13,17,19,15,18,26,25,16)(14,22,24,21,23,20,27,28)(6,9)(10,12)(14,23)(20,22)(21,28)(24,27) 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.