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)(13,14,19,22)(15,23,27,28)(16,17,21,18)(20,25,24,26)(5,6)(7,11)(8,10)(9,12)(13,15,19,27)(14,20,22,24)(16,23,21,28)(17,26,18,25)(2,4)(5,7,8,12)(6,9,10,11)(13,16)(14,18)(15,23)(17,22)(19,21)(20,25)(24,26)(27,28)(7,12)(9,11)(13,16)(14,17)(15,24)(18,22)(19,21)(20,27)(23,26)(25,28) involution — undirected(6,10)(9,11)(13,17,19,18)(14,21,22,16)(15,25,27,26)(20,23,24,28)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.