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