cannot understand how my approach should be on graph node coloring

i have a graph and i am able to input points in it. i am getting values of my graph nodes. i have choice so that user can choice which node to select first, which color to select for selected node and adjacent nodes. now what i want is, when an user will click node 1, and click on color red, then the node 1 in my graph will have red color and the adjacent node of node 1 will have different color. no adjacent sides can have the same color. and how do i define 2 adjacent nodes? thanx in advance . this is my code

   DETAILS OF PROGRAMMING
  %  storing the nodes and color of nodes
  img = imread('G.bmp');
  image(img);
  [x,y] = ginput(7)

v1 = [x(1),y(1)]
v2 = [x(2),y(2)]
v3 = [x(3),y(3)]
v4 = [x(4),y(4)]
v5 = [x(5),y(5)] 
v6 = [x(6),y(6)]
v7 = [x(7),y(7)] 

%%informed operator 
% adjacent(v1) = [v2];
% adjacent(v2) = [v1,v3,v6,v7];
% adjacent(v3) = [v2,v4,v5];
% adjacent(v4) = [v3,v6];
% adjacent(v5) = [v3,v6];
% adjacent(v6) = [v2,v4,v5,v7];
% adjacent(v7) = [v2,v6];

% uicontrol('Style', 'text',...
%        'String', 'red',... %replace something with the text you want
%        'Units','normalized',...
%        'Position', [x(1) y(1) 0.1 0.1]);

   %%giving user the choice to choose any node at first
  prompt2 = 'which node you wish to go at first? ';
  choice2 = menu('nodes in graph', 'v1', 'v2', 'v3', 'v4', 'v5', 'v6', 'v7')
  node_num = choice2

%%selecting the color for the first node that is choosen
prompt = 'what color do you wish to put to this node? ';
choice = menu('colors available', 'red', 'blue', 'cyan', 'green')
color1 = choice

switch color1
    case 1
        disp('red')
    case 2
        disp('blue')
    case 3
        disp('cyan')
    case 4
        disp('green')

end 
%%selecting the color for adjacent nodes of the selected node
prompt1 = 'what color do you wish to put to adjacent node? ';
choice1 = menu('colors available', 'red', 'blue', 'cyan', 'green')
color2 = choice1

switch color2
    case 1
        disp('red')
    case 2
        disp('blue')
    case 3
        disp('cyan')
    case 4
        disp('green')

end 

switch node_num
    case 1
        disp('v1 is color 1, adj(v1) will be  color 2')
    case 2
        disp('v2 is color 1, adj(v2) will be color 2')
    case 3
        disp('v3 is color 1, adj(v3) will be color 2')
    case 4
        disp('v4 is color 1, adj(v4) will be color 2')
    case 5
        disp('v5 is color 1, adj(v5) will be color 2')
    case 6
        disp('v6 is color 1, adj(v6) will be color 2')
    case 7
        disp('v7 is color 1, adj(v7) will be color 2')
end

if v1 == color1
    v2 == color2
end

if v2 == color1
for i = 1:7
    for j = 1:4
        for k = 1:4
    if node_num == i
        color1 == j
        color2 == k
        v(i) = color(j)
        adjacent(v(i)) = color(k)
    end
        end
    end
end
end