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