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