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