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