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