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