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