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