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