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