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