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