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