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