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