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