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