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