digraph TopLevel {
    bgcolor = lightcyan1
    fontname = Arial
    label = "test.rb"
    fontsize = 8
    node [
        fontname = Arial,
        color = black,
        fontsize = 8
    ]

    subgraph cluster_1 {
        bgcolor = palegreen1
        fontname = Arial
        color = blue
        label = "ModuleName"
        ClassName [
            style = filled,
            URL = "classes/ModuleName/ClassName.html",
            fontcolor = black,
            color = palegoldenrod,
            label = "ClassName"
        ]

    }

}