An inner graph with some arrows

subgraph.dot

digraph ciclovida {

  d -> v;
  c -> e;
  o -> i1;
  i3 -> m [label = "error"];

  v -> o [label = "Confirma"];
  e -> o [label = "ok"];

  subgraph cluster_0 {
  label = "Almacenamiento";
  i1 -> i2 [label ="error"];
  i2 -> i3 [label="error"];
  i3 -> s [ label="ok"];
  }
   i1 -> s [label =  "ok"];
   i2 -> s [ label = "ok"];

  i1 [label = "Intento 1" shape=box]
  d [label = "Documento" shape =Mdiamond]
  c [label = "Cliente" shape=Mdiamond]
  i2 [label="Intento 2" shape=box]
  i3 [label="Intento 3" shape=box]
  s [label = "Almacenado" shape=box3d color=lightgrey style=filled]
  e [label = "Endpoint" shape=invhouse color=lightgrey style=filled]
  v [ label = "Verificación" shape=invhouse color=lightgrey style=filled]
  m [ label = "Correo Informe"]
  o [ label = "Midleware" shape=box3d]
}