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