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)(18,20)(22,23)(26,28)(27,33)(32,36)(35,37)(9,11)(10,12)(13,16)(14,15)(18,20)(22,23)(25,26,30,28)(27,34,33,31)(29,32,38,36)(35,40,37,39)(10,14)(12,15)(17,18,21,20)(19,23,24,22)(25,27,30,33)(26,31,28,34)(29,37,38,35)(32,40,36,39)(1,2)(3,5)(4,6)(7,8)(9,10)(11,12)(13,14)(15,16)(17,19,21,24)(18,22,20,23)(25,28,30,26)(27,31,33,34)(29,36,38,32)(35,39,37,40)(1,3,4,7)(2,5,6,8)(9,12)(10,11)(13,15)(14,16)(17,20,21,18)(19,23,24,22)(25,29,30,38)(26,32,28,36)(27,35,33,37)(31,39,34,40)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.