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