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