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