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