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