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