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