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