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