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