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