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