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