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