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