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