SHE WAS simultaneously without pretense and a gifted politician who could, in yellow canvas sneakers on a summer day, accept her party's nomination for governor and accept her vanquished challenger as her ticket-mate for lieutenant governor.

She was the proud product of arguably the nation's leanest state political machine. Yet the leaders of that machine, including the late Connecticut and national Democratic chairman, John Bailey, and former senator Abraham Ribicoff, were among the last to be persuaded that Ella Grasso could win the governorship.

John Bailey, of all people, should have known better. After all, his guidance and imagination helped elect Connecticut's first Jewish governor and first black constitutional officer as well as the country's first Catholic president. But no Italian American had ever been elected governor, to say nothing of one who happened to be also a woman.

And it wasn't only Connecticut in 1974; no woman had ever before been elected governor of any state without succeeding her husband. Ella Tambussi Grasso, whose Italian immigrant parents had sent her to Mount Holyoke College, had spent her life succeeding -- not succeeding someone else -- just succeeding.

In the state legislature, she became the first female majority leader. In two of her three winning races for secretary of state, Mrs. Grasso was the state's top vote-getter. After two terms in the U.S. House of Representatives, she sought the governorship. Jokes about Connecticut's voters being too old for a "governess" failed to catch on. She routed her Republican opponent.

Against the cancer that took her life last week, Ella Grasso was to battle with the same remarkable spirit and determiniation. Because of that cancer, she had resigned the governorship -- to which she had been reelected in 1978 -- on New Year's Eve.

Characteristic of Mrs. Grasso were the words she had spoken to a male reporter during her first gubernatorial campaign, when others were making her sex an issue: "I really don't want to be a female chauvinist, but I always get unstrung when people think the qualities of compassion, integrity, thoughtfulness and understanding belong to the women only. I feel sorry for you guys . . . " Ella Grasso was no female chauvinist. She was the governor.