Marion Hicks was a real estate developer from Los Angeles, John Grayson was an architect. They were partners with J.Kell Houssels in building the El Cortez.

Somewhere around 1944-1945 Bugsy Siegel bought out their shares, so I think your napkin would be from the 1941-1945 era.

It's a beautiful napkin!!

source: Steve Ficher's "When the Mob Ran Vegas"