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