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