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