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