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