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