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