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