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