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