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