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