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