How can I define which node goes next to another one in grViz

Question

I am trying to plot a regular graph with grViz in R like the below:

using the following code:

grViz("
graph {

# a graph statement
graph [layout = circo]

# a node statement
node [shape = circle,
      style = filled,
      color = grey,
      fillcolor = orange];
nodesep=4
A; B; C; D; E; F; G; H;

# an edge statement
edge [color = grey]

A -- B
B -- C
C -- D
D -- E
E -- F
F -- G
G -- H
H -- A
A -- D
H -- E
B -- G
C -- F
}")

However, I cannot place the nodes in sequential order despite trying the different options for rankdir: