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