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