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