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