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