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