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