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