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