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