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