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