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