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