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