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