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