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