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