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