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