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