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)(13,15,18,26)(14,20,23,21)(16,17,25,19)(22,28,24,27)(5,7,8,11)(6,10,9,12)(13,16,19,15,18,25,17,26)(14,21,24,27,23,20,22,28)(2,4)(13,16,19,15,18,25,17,26)(14,21,24,27,23,20,22,28)(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.