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)(15,21)(16,19)(17,20)(18,23)(22,25)(24,27)(26,28) involution — undirected(6,9)(10,12)(13,15)(14,18)(16,22)(17,23)(19,26)(20,21)(24,28)(25,27) involution — undirected(1,2,3,4)(7,11)(10,12)(13,16)(14,19)(15,22)(17,24)(18,25)(20,27)(21,26)(23,28)(5,7,8,11)(6,10,9,12)(16,24)(19,27)(22,28)(25,26)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.