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