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