Use highchart advanced property:

<hc:chartProperty name="colors">
<hc:propertyExpression><![CDATA[java.util.Arrays.asList("#1e8cff","#ff1e1e","#a3d900","#ff9d0a","#00ffff","#ff00ff","#00ff00","#800000","#cc99ff","#bfbfbf")]]></hc:propertyExpression>
</hc:chartProperty>

If you will have more series then colors in list then list will be restarted. So you would have more series with the same color in such a case.