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