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