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)(16,21)(17,27)(18,20)(19,25)(22,24)(26,28)(6,9)(7,11)(13,15,24,26,18,16,17,25)(14,19,27,21,20,28,22,23)(2,4)(5,6)(7,10)(8,9)(11,12)(14,20)(15,16)(22,27)(25,26) involution — undirected(6,9)(10,12)(13,16,18,15)(14,21,20,23)(17,25,24,26)(19,22,28,27)(5,7,8,11)(6,10,9,12)(14,20)(19,28)(21,23)(22,27)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.