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