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