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