“People I love most,” said Diego Rivera, “think I look like a frog.” A large frog, apparently, for at age 20 he was more than six feet tall and weighed over 300 pounds. But Rivera’s outsize physique was more than matched by his prodigious talent and adventurous spirit, as Susan Goldman Rubin’s new biography makes clear. Enhanced by gorgeously reproduced photos and artwork, Rubin’s account follows the Mexican artist from his early drawings — as a small child, he was given free rein in a room “covered with black canvas as high as he could reach” — through his eventful, productive life. Rubin describes Rivera’s turbulent romantic history, but she focuses on his extraordinary paintings and murals, in which he exalted Mexico’s past as well as the world’s laborers. She particularly delves into the stories behind Rivera’s National Palace murals, his Detroit Industry series and his doomed Rockefeller Center mural. The book’s last full-color image is a detail from “Dream of a Sunday Afternoon in Alameda Park.” Young readers will enjoy seeing individuals Rubin has introduced them to, including Rivera’s favorite Mexican folk artist, Jose Guadalupe Posada, who stands next to one of his own full-size skeleton figures, who holds hands with a prepubescent Rivera (complete with striped socks and knickers), who stands in front of Frida Kahlo, the love of his life. And then there’s Rivera’s look-alike: a frog, emerging from his jacket pocket.