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