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