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