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