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