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)(13,14,20,24,18,22,19,23)(15,21,25,16,17,27,28,26)(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15)(14,21)(16,24)(17,18)(19,28)(20,25)(22,27)(23,26) involution — undirected(2,4)(5,8,9,6)(7,11,12,10)(13,16,18,26)(14,15,22,17)(19,21,20,27)(23,28,24,25)(2,4)(7,12)(10,11)(13,17)(14,16)(15,18)(19,28)(20,25)(21,24)(22,26)(23,27) 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.