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