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