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