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