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