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