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