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