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