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