static void Main(string[] args)
{
    const ConsoleColor redColor = ConsoleColor.Red;
    const ConsoleColor greenColor = ConsoleColor.Green;
    const ConsoleColor blueColor = ConsoleColor.Blue;

    const string MenuRedColor = "1";
    const string MenuGreenColor = "2";
    const string MenuBlueColor = "3";

    Console.WriteLine($"У нас на выбор имеются следующие цвета:" +
        $"{redColor}," +
        $"{greenColor}," +
        $"{blueColor},");

    switch (Console.ReadLine())
    {
        case MenuRedColor:
            Console.ForegroundColor = redColor;
            break;
        case MenuGreenColor:
            Console.ForegroundColor = greenColor;
            break;
        case MenuBlueColor:
            Console.ForegroundColor = blueColor;
            break;
    }
}