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