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