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