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