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