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