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