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