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