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