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