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