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