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)(13,14,17,21,18,22,15,19)(16,20,24,27,25,28,23,26)(5,6)(7,11)(8,10)(9,12)(14,19)(15,17)(16,24)(21,22)(23,25)(26,27) involution — undirected(1,2,3,4)(5,7)(6,9)(8,12)(10,11)(13,15,18,17)(14,19,22,21)(16,24,25,23)(20,27,28,26)(7,12)(9,11)(13,16,17,24,18,25,15,23)(14,20,21,27,22,28,19,26)(6,10)(9,11)(13,15,18,17)(14,19,22,21)(16,24,25,23)(20,27,28,26)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.