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