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