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