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)(25,26,30,29)(27,32,35,31)(28,36,37,33)(34,38,40,39)(3,7)(5,8)(9,11)(10,13)(12,15)(14,18)(16,19)(17,21)(20,23)(22,24)(25,27,30,35)(26,31,29,32)(28,34,37,40)(33,38,36,39)(1,2)(3,5)(4,6)(7,8)(10,16)(11,12)(17,24)(18,20)(25,27,30,35)(26,31,29,32)(28,34,37,40)(33,38,36,39)(1,3,4,7)(2,5,6,8)(9,12,15,11)(10,13,16,19)(14,18,23,20)(17,22,24,21)(25,27)(26,32)(28,34)(29,31)(30,35)(33,39)(36,38)(37,40)(1,2)(3,5)(4,6)(7,8)(9,13)(10,11)(12,16)(14,22)(15,19)(17,20)(18,24)(21,23)(25,28,30,37)(26,33,29,36)(27,34,35,40)(31,38,32,39)(9,14,15,23)(10,17,16,24)(11,18,12,20)(13,21,19,22)(25,29,30,26)(27,32,35,31)(28,33,37,36)(34,38,40,39)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.