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