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)(23,24)(25,26,31,29)(27,32,36,30)(28,37,39,33)(34,38,35,40)(3,7)(5,8)(9,10,14,11)(12,15,20,17)(13,16,22,18)(19,23,21,24)(25,27)(26,32)(28,35)(29,30)(31,36)(33,38)(34,39)(37,40)(1,2)(3,5)(4,6)(7,8)(25,28)(26,33)(27,34)(29,37)(30,38)(31,39)(32,40)(35,36) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,29,31,26)(27,32,36,30)(28,37,39,33)(34,40,35,38)(1,2)(3,5)(4,6)(7,8)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,28)(26,33)(27,35)(29,37)(30,40)(31,39)(32,38)(34,36)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(25,30,31,32)(26,27,29,36)(28,38,39,40)(33,34,37,35)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.