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