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