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