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