Riley Keough Celebrates Directorial Debut of War Pony at Cannes Alongside Elvis : 'In Shock'

Vittorio Zunino Celotto/Getty for Kering

Riley Keough's co-directorial debut at this year's Cannes Film Festival has special significance to the actress.

The 32-year-old granddaughter of Elvis Presley, whose film War Pony screened at the festival on Saturday, also celebrated the Cannes debut of Baz Luhrmann's Elvis, a new film starring Austin Butler as the eponymous rockstar.

Cannes Film Festival director Thierry Fremaux said it was a "happy coincidence" that Keough's first film was part of the festival in the same year her grandfather's life was also highlighted.

Keough co-directed the film alongside Gina Gammell, another first-time director.

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Keough, who chose a black blazer with matching shorts and Dior heels for the screening, said she was "in shock" to be at the festival.

"We're really just grateful to be here," Keough said for the entire cast and crew. "This was a collaboration between all of us, and this is all of our film."

War Pony, which stars first-time actor Jojo Bapteise Whiting, follows 23-year-old Bill, a Oglala-Lakota native navigating growing up on a reservation, all while always trying to find his next hustle.

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Although Whiting couldn't be in attendance at the debut, his mother, Tonya Masten, brought her son to the big event in the form of a framed photo.

"The movie was incredible, incredible, incredible," Masten shared. "It was moving and that's what is so important about it is, because it's real. It's the hardships that we go through, through everything. This movie told what we go through ... on reservations."

After the film screening, the applause lasted for nearly six minutes. As cheers died down, Keough hugged everyone who had shared the stage with her, including Masten, who was in tears.

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"I'm very overwhelmed. I haven't really taken it all in yet," Keough told PEOPLE. "It's been wonderful ... we're just excited."

The Zola star also shared that her family, including mother Lisa Marie Presley and grandmother Priscilla Presley, were not at the screening "at the moment."