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