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