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