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