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