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