Run with all the defaults:

Task("Use-Defaults")
    .Does(() => {
        AutoRest.Generate("./sample.json");
});

Configure using AutoRestSettings object

Task("Settings-Object")
.Does(() => {
var settings = new AutoRestSettings {
    Namespace = "Cake",
    Generator = CodeGenerator.AzureCSharp,
    ClientName = "Cake.AutoRest",
    HeaderComment = "Generated by Cake.AutoRest",
    OutputDirectory = "./dist/client"
    };
    AutoRest.Generate("./sample.json", settings);
});

Configure using fluent interface (equivalent to above)

Task("Fluent-Interface")
.Does(() => {
    AutoRest.Generate("./sample.json", settings =>
        settings.UseNamespace("Cake")
            .UseClientName("Cake.AutoRest")
            .AddHeaderComment("Generated by Cake.AutoRest")
            .WithGenerator(CodeGenerator.AzureCSharp)
            .OutputToDirectory("./dist/client"));
});