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