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