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