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