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