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