One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8)(3,6,4,7)(9,10,14,17)(11,18,20,23)(12,16,13,21)(15,22,24,19)(28,35)(30,37)(31,36)(33,39)(2,6)(3,4)(7,8)(9,11)(10,15)(12,19)(13,22)(14,20)(16,23)(17,24)(18,21)(25,26)(27,30)(28,36)(29,32)(31,35)(33,40)(34,37)(38,39) involution — undirected(2,7)(3,4)(6,8)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,24,18)(25,27,29,34)(26,30,32,37)(28,33,35,39)(31,38,36,40)(2,8)(6,7)(11,20)(15,24)(18,23)(19,22)(25,28,29,35)(26,31,32,36)(27,33,34,39)(30,38,37,40)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.