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