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