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