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