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