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