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