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