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