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