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