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