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