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