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