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