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