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