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