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