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