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)(16,24)(17,18)(20,25)(21,22)(23,28)(26,27) involution — undirected(5,6,8,9)(7,10,11,12)(14,18)(15,21)(20,24)(23,27)(2,4)(13,14)(15,22)(16,20)(17,18)(19,21)(23,28)(24,25)(26,27) involution — undirected(1,2)(3,4) involution — undirected(13,15,17,21)(14,19,18,22)(16,23,25,27)(20,26,24,28)(5,7,8,11)(6,10,9,12)(13,16,17,25)(14,20,18,24)(15,23,21,27)(19,26,22,28)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.