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