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