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