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