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