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