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