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