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