The final roster moves come after receiver Kenny Stafford and linebacker Kevin Brown II, also CFL veterans, were let go earlier.
Lemon signed a one-year contract with Edmonton in February. The six-foot-two, 248-pound defensive lineman has played nine CFL seasons, registering 70 career sacks and 22 forced fumbles over 107 regular-season games.
Lemon is a two-time Grey Cup champion with Calgary (2014) and Toronto (2017).
The six-foot-two, 230-pound Diggs, a linebacker, was Edmonton s outstanding rookie nominee in 2019 after recording 73 tackles, 11 special-teams tackles, one interception and two sacks.
The six-foot-seven, 320-pound Coleman was in his second stint with Edmonton. The towering offensive lineman had played for the franchise from 2013-16 before joining the Saskatchewan Roughriders (2016-19).
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