How would I stop an random colour randomise from picking the same colour twice

<script>
      function randomColour(){
        var colour=[];
        colour[0]= '#edf2fb';
        colour[1]= '#d7e3fc';
        colour[3]= '#c1d3fe';
        colour[4]= '#d1d1d1';
        colour[5]= '#e1dbd6';
        colour[6]= '#e2e2e2';
        colour[7]= '#f9f6f2';
        colour[8]='#ffc09f';
        colour[9]='#ffee93';
        colour[10]='#fcf5c7';
        colour[11]='#a0ced9';
        colour[12]='#adf7b6';
        colour[13]='#809bce';
        colour[14]='#95b8d1';
        colour[15]='#b8e0d2';
        colour[16]='#d6eadf';
        colour[17]='#eac4d5';
        colour[18]='#e8d1c5';
        colour[19]='#eddcd2';
        colour[20]='#fff1e6';
        colour[21]='#f0efeb';
        colour[22]='#eeddd3';
        colour[23]='#e8dff5';
        colour[24]='#fce1e4';
        colour[25]='#fcf4dd';
        colour[26]='#ddedea';
        colour[27]='#daeaf6';
        colour[28]='#d3ab9e';
        colour[29]='#eac9c1';
        colour[30]='#ebd8d0';
        colour[31]='#ffe5ec';
        colour[32]='#ffc2d1';
        colour[33]='#ceb5b7';
        colour[35]='#b5d6d6';
        colour[36]='#f2f5ff';
        colour[37]='#efcfe3';
        colour[38]='#eaf2d7';
        colour[39]='#b3dee2';
        colour[40]='#f8ad9d';
        colour[41]='#fbc4ab';
        colour[42]='#ffdab9';
        colour[43]='#cdb4db';
        colour[44]='#ffc8dd';
        colour[45]='#ffafcc';
        colour[46]='#bde0fe';
        colour[47]='#a2d2ff';
        colour[48]='#fdffb6';
        colour[49]='#caffbf';
        colour[50]='#9bf6ff';
        colour[51]='#a0c4ff';
        colour[52]='#ffc6ff';
        colour[53]='#a7bed3';
        colour[54]='#c6e2e9';
        colour[55]='#f1ffc4';
        colour[56]='#ffcaaf';
        colour[57]='#dab894';
        colour[58]='#fec7bc';
        colour[59]='#fcf5ee';
        var pick= Math.floor(Math.random()*60);
        var test = document.getElementById("colorpad");
        test.style.backgroundColor = colour[pick];
        return colour[pick];


      }
    </script>

I would like to know on how I would be able to stop this random colour picker from choosing the same colour twice because it is currently doing this when I want it to pick another random colour. I do not know why this is occurring, what should I implement into my code to stop this from occurring.