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