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