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