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