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