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