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