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