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