Display div if option is selected in jQuery

I am trying to display a div if one of 2 options is selected on my page. Here is the select menu:

<select id="graph_select">
<option id="pilot_form">Pilot Hours</option>
<option id="client_form">Client Hours</option>
</select>

Here is my first div for the first option:

<div id="pilot_graph_form" align="center" style="margin:0 auto; display:none;">
        <form action="?page=reporter" method="POST" name="graph_form">
            <p>From:</p>
            <select name="start_date">
                <cfloop query="date_worked_menu">
                    <option>#date_worked_menu.date_worked#</option>
                </cfloop>
            </select>
            <br />
            <br />
            <p>To:</p>
            <select name="end_date">
                <cfloop query="date_worked_menu">
                    <option>#date_worked_menu.date_worked#</option>
                </cfloop>   
            </select>
            <br />
            <input class="btn btn-success" type="Submit" name="submit_to_graph" value="Submit" id="submit_to_graph">
        </form>
    </div>

Here is the div for my second option:

<div id="client_graph_form" align="center" style="margin:0 auto; display:none;">
        <form action="?page=reporter" method="POST" name="graph_form_clients">
            <p>From:</p>
            <select name="client">
                <cfloop query="client_menu">
                    <option value="#client_menu.id#">#client_menu.name#</option>
                </cfloop>
            </select>
            <input class="btn btn-success" type="Submit" name="submit_to_graph" value="Submit" id="submit_to_graph">
        </form>
    </div>