From Wikipedia:

"Graphviz (short for Graph Visualization Software) is a package of open-source tools [...] for drawing graphs specified in DOT language scripts."

Install the graphviz package.

Viewers:

• KGraphViewer — Graphviz DOT graph file viewer from KDE.

https://apps.kde.org/kgraphviewer/ || kgraphviewer

• xdot.py — Interactive viewer for graphs written in Graphviz's dot language (built on GTK).

https://github.com/jrfonseca/xdot.py || xdot

You need to install a font to include strings in the graph. For information how to install fonts, see Fonts.

To see what fonts are available:

$ fc-list

To see what fonts dot is using:

$ dot example.gv -Tpng -o foo.png -v 2>&1 | grep font

Here is a dot file example.

example.gv

digraph graph_name {
 graph [
 charset = "UTF-8";
 label = "sample graph",
 labelloc = "t",
 labeljust = "c",
 bgcolor = "#343434",
 fontcolor = white,
 fontsize = 18,
 style = "filled",
 rankdir = TB,
 margin = 0.2,
 splines = spline,
 ranksep = 1.0,
 nodesep = 0.9
 ];

 node [
 colorscheme = "rdylgn11"
 style = "solid,filled",
 fontsize = 16,
 fontcolor = 6,
 fontname = "Migu 1M",
 color = 7,
 fillcolor = 11,
 fixedsize = true,
 height = 0.6,
 width = 1.2
 ];

 edge [
 style = solid,
 fontsize = 14,
 fontcolor = white,
 fontname = "Migu 1M",
 color = white,
 labelfloat = true,
 labeldistance = 2.5,
 labelangle = 70
 ];

 // node define
 alpha [shape = box];
 beta [shape = box];
 gamma [shape = Msquare];
 delta [shape = box];
 epsilon [shape = trapezium];
 zeta [shape = Msquare];
 eta;
 theta [shape = doublecircle];

 // edge define
 alpha -> beta [label = "a-b", arrowhead = normal];
 alpha -> gamma [label = "a-g"];
 beta -> delta [label = "b-d"];
 beta -> epsilon [label = "b-e", arrowhead = tee];
 gamma -> zeta [label = "g-z"];
 gamma -> eta [label = "g-e", style = dotted];
 delta -> theta [arrowhead = crow];
 zeta -> theta [arrowhead = crow];
}

To generate a png image from this file:

$ dot -Tpng example.gv -o example.png

• The official Graphviz website