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