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