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