Hi you can do one thing. Create a user control and put the below code as:
<asp:Menu ID="mnuMainMenu" runat="server" Orientation="Horizontal" MaximumDynamicDisplayLevels="1"
StaticMenuItemStyle-Width="100%" DynamicEnableDefaultPopOutImage="True" StaticPopOutImageUrl="~/Images/divider.gif"
CssClass="MyMenuStatic" PathSeparator="," DynamicVerticalOffset="2" DynamicMenuStyle-BorderWidth="1"
StaticBottomSeparatorImageUrl="Images/seprator-vertical.GIF">
<StaticHoverStyle CssClass="MyMenuStatic" />
<StaticMenuItemStyle CssClass="MyMenuStatic" />
<DynamicMenuItemStyle CssClass="MyMenuDynamic" />
<DynamicHoverStyle CssClass="MyMenuDynamicHover" />
<Items>
<asp:MenuItem Text="Parent menu1" Selectable="true" NavigateUrl="javascript:DoNothing()">
<asp:MenuItem Text="Chlid Menu1" NavigateUrl="javascript:ChlidMenu1Requirements()">
<asp:MenuItem Text="Grand Child1" SeparatorImageUrl="~/Images/seprator.gif" NavigateUrl="javascript:GrandChild1()">
</asp:MenuItem>
<asp:MenuItem Text="Grand Child2" SeparatorImageUrl="~/Images/seprator.gif" NavigateUrl="javascript:GrandChild2()">
</asp:MenuItem>
</asp:MenuItem>
</asp:MenuItem>
<asp:MenuItem Text="Parent menu2" Selectable="true" NavigateUrl="javascript:DoNothing()">
<asp:MenuItem Text="Chlid Menu2" NavigateUrl="javascript:ChlidMenu2Requirements()">
<asp:MenuItem Text="Grand Child3" SeparatorImageUrl="~/Images/seprator.gif" NavigateUrl="javascript:GrandChild3()">
</asp:MenuItem>
</asp:MenuItem>
</asp:MenuItem>
<asp:MenuItem Text="Parent menu3" Selectable="true" NavigateUrl="javascript:DoNothing()">
<asp:MenuItem Text="Chlid Menu4" NavigateUrl="javascript:ChlidMenu2Requirements()">
</asp:MenuItem>
</asp:MenuItem>
</Items>
</asp:Menu>
Now few more steps you need to follow
a) find 2 small images 1) separator and 2) small divider
b) menu styling has to be done using css