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