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