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