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