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