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