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