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