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