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