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