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