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