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