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