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