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