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