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