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