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