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