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