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