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