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