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