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