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