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