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