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)(27,34)(28,33)(29,32)(30,31)(35,40)(36,39)(37,38) involution — undirected(1,2)(3,8)(4,6)(5,7)(9,11,14,19)(10,15,12,16)(13,18,21,24)(17,22,20,23)(27,29)(32,34)(35,36)(39,40)(1,3)(2,4)(5,6)(7,8)(10,12)(13,21)(15,16)(18,24)(25,27,31,29)(26,32,30,34)(28,36,38,35)(33,40,37,39)(3,6)(4,8)(9,12,14,10)(11,16,19,15)(13,20,21,17)(18,23,24,22)(25,28,31,38)(26,33,30,37)(27,35,29,36)(32,39,34,40)(1,4,5,8)(2,6,7,3)(9,11)(10,16)(12,15)(13,18)(14,19)(17,23)(20,22)(21,24)(25,29,31,27)(26,32,30,34)(28,35,38,36)(33,40,37,39)(1,2)(3,8)(4,6)(5,7)(9,13)(10,17)(11,18)(12,20)(14,21)(15,22)(16,23)(19,24)(25,30,31,26)(27,32,29,34)(28,37,38,33)(35,39,36,40)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.