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