A <a href="https://en.wikipedia.org/wiki/1-planar_graph" class="extiw" title="en:1-planar graph">1-planar</a> drawing of the <a href="https://en.wikipedia.org/wiki/Tur%C3%A1n_graph" class="extiw" title="en:Turán graph">hyperoctahedral graph</a> <i>K</i><sub>2,2,2,2</sub>. Each of its eight vertices is adjacent to the six vertices with different colors from it, but not to the one other vertex with the same color.
<a href="//commons.wikimedia.org/wiki/User:David_Eppstein" class="mw-redirect" title="User:David Eppstein">David Eppstein</a>
<span class="int-own-work" lang="en">Own work</span>