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