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)(11,15)(12,17)(13,23)(14,16)(18,20)(19,24)(21,22)(25,26,31,35)(27,36,37,32)(28,30,34,40)(29,38,39,33)(1,2)(3,5)(4,6)(7,8)(9,11)(10,15)(12,20)(13,21)(14,19)(16,24)(17,18)(22,23)(25,27)(26,32)(28,38)(29,30)(31,37)(33,34)(35,36)(39,40) involution — undirected(1,3,4,7)(2,5,6,8)(10,16)(11,19)(13,20)(17,22)(27,37)(29,39)(32,36)(33,38)(9,12,14,21)(10,17,16,22)(11,20,19,13)(15,18,24,23)(25,28)(26,30)(27,38)(29,32)(31,34)(33,37)(35,40)(36,39)(9,13,14,20)(10,18,16,23)(11,21,19,12)(15,17,24,22)(25,29)(26,33)(27,30)(28,36)(31,39)(32,34)(35,38)(37,40)(9,10)(11,15)(12,22)(13,18)(14,16)(17,21)(19,24)(20,23)(25,30)(26,34)(27,29)(28,35)(31,40)(32,33)(36,38)(37,39) involution — undirectedA 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.