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