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)(11,14)(12,15)(13,18)(16,21)(17,20)(19,23)(22,24)(25,26)(27,32)(28,30)(29,34)(31,33)(35,40)(36,39)(37,38) involution — undirected(2,5)(6,7)(9,10,14,11)(12,17,20,15)(13,16,21,18)(19,23,24,22)(25,27)(26,32)(28,37)(29,35)(30,38)(31,36)(33,39)(34,40)(1,2)(3,6)(4,5)(7,8)(10,11)(15,17)(16,18)(22,23)(26,33)(27,36)(28,35)(34,38) involution — undirected(1,3,4,8)(2,6,5,7)(9,11,14,10)(12,17,20,15)(13,18,21,16)(19,23,24,22)(25,28,31,35)(26,30,33,40)(27,37,36,29)(32,38,39,34)(9,12)(10,15)(11,17)(13,19)(14,20)(16,22)(18,23)(21,24)(25,29,31,37)(26,34,33,38)(27,28,36,35)(30,39,40,32)(9,13,14,21)(10,16,11,18)(12,19,20,24)(15,22,17,23)(25,30)(26,35)(27,38)(28,33)(29,32)(31,40)(34,36)(37,39)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.