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