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