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