nodes
node in default style
client
server

node stroke color
client[color=red]
server[color=blue]

node filled color
client[style=filled fillcolor=yellow]

node label
client[label="Remote client"]
node shape
client[shape="circle"]
node size
digraph Graph {
node[shape=rect]
splines=ortho
gateway[width=3 height=0.3]
gateway -> users
gateway -> companies
gateway -> groups
}

edges
edge in default style
client -> server
edge label
client -> server[label='send request']
edge style
client -> server[style=dashed],
client -> server[style=dotted]
edge color
client -> server[color=green]
subgraphs/groups
subgraph
{
node [color=red]
javascript -> api
}
subgraph server{
edge [style=dashed]
api -> backend
}

subgraph named cluster* is a cluster
subgraph cluster_0 {
style=filled;
color=lightgrey;
javascript -> api;
label = "frontend";
}

defaults
set default style for all nodes
node[style=filled];
set default style for all edges
edge[style=dotted];