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