[MaestroX]

Sure,

Go to: Styles & Templates -> Style Manager -> Your Style -> Edit Templates

in your footer template find:

 <if condition="$show['quickchooser']">
  <td class="tfoot">
   <select name="styleid" onchange="switch_id(this, 'style')">
    <optgroup label="$vbphrase[quick_style_chooser]">
     $quickchooserbits
    </optgroup>
   </select>
  </td>
 </if>

and change it to:

 
<if condition="is_member_of($vbulletin->userinfo, x)">
 <if condition="$show['quickchooser']">
  <td class="tfoot">
   <select name="styleid" onchange="switch_id(this, 'style')">
    <optgroup label="$vbphrase[quick_style_chooser]">
     $quickchooserbits
    </optgroup>
   </select>
  </td>
 </if>
</if>

change x to the usergroup id of the the users who you want to let use the new style