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