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