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