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