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