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