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