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