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