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