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