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