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