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