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