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)(11,17)(12,20)(13,14)(15,19)(16,21)(18,22)(23,24)(25,26,31,36)(27,35,30,32)(28,29,34,33)(37,40,39,38)(1,2,4,6)(3,5,8,7)(9,10)(11,15)(12,20)(13,14)(16,21)(17,19)(18,23)(22,24)(25,27,31,30)(26,32,36,35)(28,39,34,37)(29,40,33,38)(1,2)(3,5)(4,6)(7,8)(10,14)(15,17)(16,20)(22,23)(25,28,31,34)(26,33,36,29)(27,37,30,39)(32,40,35,38)(1,3,4,8)(2,5,6,7)(9,10)(11,15)(12,16)(13,14)(17,19)(18,22)(20,21)(23,24)(25,27,31,30)(26,32,36,35)(28,37,34,39)(29,38,33,40)(9,11)(10,15)(12,18)(13,19)(14,17)(16,22)(20,23)(21,24)(25,29,31,33)(26,34,36,28)(27,38,30,40)(32,39,35,37)(9,12,13,21)(10,16,14,20)(11,18,19,24)(15,22,17,23)(25,30,31,27)(26,35,36,32)(28,39,34,37)(29,40,33,38)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.