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