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