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