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)(11,19)(12,23,25,35)(13,17)(14,18)(15,21)(16,26,32,29)(20,37,24,40)(22,34)(27,33)(28,31)(30,39,36,38)(2,5)(6,7)(9,11)(10,15)(12,24,25,20)(13,21)(14,28)(16,30,32,36)(17,19)(18,34)(22,27)(23,37,35,40)(26,38,29,39)(31,33)(9,12)(10,16)(11,20)(13,25)(14,29)(15,30)(17,32)(18,35)(19,36)(21,24)(22,39)(23,33)(26,27)(28,38)(31,37)(34,40) involution — undirected(1,3,4,8)(2,6,5,7)(10,17)(15,19)(16,32)(18,33)(23,35)(30,36)(31,34)(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.