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