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