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