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