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