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