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