The Labor Department inspector general's office, working with the Internal Revenue Service, has unearthed the largest case of embezzlement by a department employe in the history of the IG's office.

Maggielean President, 49, who worked as a clerk for the department in Chicago, has pleaded guilty to stealing more than $585,000 from the government between 1975 and 1980. She faces a maximum of 420 years in prison and $328,000 in fines when she is sentenced Sept. 20 on 56 counts of mail fraud and theft and two counts of tax evasion.

In her job, President was able to reactivate old workmen's-compensation files and create spurious disability claims that she processed and sent to the Treasury Department for reimbursement, officials said. The checks were sent to President, under her name or an alias, and two associates, who still are awaiting arraignment.

In related civil proceedings to recover the stolen assets, the department has attached two automobiles purchased by President, two residences, one tractor-trailer and one refrigerator trailer. The government plans to auction off the property and hopes to earn about half a million dollars. Said one official, "I wonder if we got the slides of her Mediterranean cruises." HIRING VETS . . .

In ceremonies at the department Monday, Donald Briggs of Cleveland was among those honored in connection with "Hire a Vet" month because, while lining up a job interview for a veteran, Briggs gave him the shirt off his back.

Briggs was one of 29 state Job Service employes from nine states who were honored for their efforts to find jobs for veterans with private industry. The program is financed by the department.

When former Marine David Branthoover showed up at Briggs' office to seek help in finding a job, he told Briggs (who is also a veteran) that he had neither a dress shirt nor a tie to wear to an interview. Briggs peeled off both items; Branthoover went to the inverview and got the job, repairing coin-operated copiers and video machines for a small Cleveland company whose owner is also a veteran. Branthoover was on hand for the tribute Monday. Secretary Raymond J. Donovan recently squared off against AFL-CIO President Lane Kirkland in a guest column printed in the Los Angeles Times.

Kirkland had weighed in with a blunt Labor Day attack on Reagan administration policies affecting working people: "For three years in a row, the meaning of Labor Day has been dishonored by a president who professes warm regard for working people on that one day and exhibits icy disdain for them on the other 364."

Donovan, a point man for the Reagan-Bush reelection campaign on labor issues, retorted last weekend. Kirkland, he said, had "scored a 10 -- in the rhetorical pentathalon. He vaulted over inconvenient facts, raced to inaccurate conclusions, shot from the hip, fenced himself in and leaped to new heights of political vehemence." NEW FACE . . .

Donovan has named Elizabeth Z. Doyle to replace Paul Russo as deputy undersecretary of labor for intergovernmental affairs. Doyle formerly specialized in intergovernmental affairs at the Education and Health and Human Services departments and also worked for the Reagan-Bush campaign in New York state in 1980.

Russo has become labor liaison for the Reagan-Bush reelection campaign. TO THE RESCUE . . .

Because of a cut in federal funds after Congress approved a new allocation formula, the New York State Department of Labor announced recently that it would have to cut 370 employes who help find jobs for the unemployed.

The new formula, approved by Congress in 1982, was an attempt to "come up with a more standard, objective way" of allocating money to the states under the 1933 Wagner-Peyser Act, which set up a national system of public employment offices, according to an official of Labor's Employment and Training Administration.

While other states stood to lose a higher proportion of their funds, New York stood to lose the most money -- reportedly about $8 million. It was, according to one official, "the only state going around screaming."

In any case, Congress has come to the rescue with a $20 million supplemental appropriation that restored much of the lost funds to give states more time to adjust.