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