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