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