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)(14,19)(15,23)(16,25)(20,22) involution — undirected(5,7,8,12)(6,9,10,11)(13,14,17,19)(15,21,23,27)(16,26,25,28)(18,20,24,22)(2,4)(14,20)(15,23)(18,24)(19,22)(21,28)(26,27) involution — undirected(6,10)(9,11)(13,15)(14,21)(16,18)(17,23)(19,27)(20,26)(22,28)(24,25) involution — undirected(7,12)(9,11)(13,16,17,25)(14,21,19,27)(15,24,23,18)(20,28,22,26)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.