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)(13,14,19,21,18,22,16,25)(15,20,23,17,24,28,26,27)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,26)(17,21)(18,24)(19,23)(22,28)(25,27) involution — undirected(1,2,3,4)(6,10)(9,11)(13,16,18,19)(14,21,22,25)(15,23,24,26)(17,20,27,28)(7,12)(9,11)(15,24)(17,27)(20,28)(23,26) involution — undirected(6,10)(9,11)(13,17,19,28,18,27,16,20)(14,15,21,23,22,24,25,26)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.