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