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