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