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