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