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)(11,13)(12,15)(14,20)(16,18)(17,22)(19,23)(21,24)(25,26,31,34)(27,32,30,40)(28,33,38,29)(35,36,37,39)(1,3)(2,6)(4,7)(5,8)(9,11)(10,16)(12,13)(14,19)(15,18)(17,23)(20,21)(22,24)(25,27,31,30)(26,32,34,40)(28,35,38,37)(29,39,33,36)(10,12)(11,18)(17,20)(19,24)(25,28,31,38)(26,29,34,33)(27,35,30,37)(32,39,40,36)(2,7)(4,6)(9,12,15,10)(11,13,18,16)(14,20,22,17)(19,21,24,23)(25,28)(26,33)(27,35)(29,34)(30,37)(31,38)(32,36)(39,40)(1,4,5,6)(2,3,7,8)(9,13)(10,11)(12,18)(14,21)(15,16)(17,19)(20,24)(22,23)(25,29,31,33)(26,28,34,38)(27,36,30,39)(32,37,40,35)(1,3)(2,4)(5,8)(6,7)(9,14,15,22)(10,17,12,20)(11,19,18,24)(13,21,16,23)(25,30,31,27)(26,32,34,40)(28,37,38,35)(29,39,33,36)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.