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