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