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)(15,20)(16,26)(17,27)(18,22)(19,23)(21,24)(25,28) involution — undirected(5,6,8,9)(7,10,11,12)(13,15,18,24,19,16,17,25)(14,20,22,21,23,26,27,28)(7,11)(10,12)(13,16)(14,21)(15,19)(17,25)(18,24)(20,22)(23,28)(26,27) involution — undirected(2,4)(5,7,8,11)(6,10,9,12)(13,17,19,18)(14,22,23,27)(15,24,16,25)(20,28,26,21)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.