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