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