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