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