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