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