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