It didn't remind me at all of Caylus. (Except insofar as they are both labeled "worker placement games", same as Agricola, Factory Manager, Stone Age, ... if all these games feel the same to you, then maybe Magnum Sal will too!
To me, the core of Caylus is about players placing workers in turn, and then resolving the actions (after all players' worker placement is finished) in the building order specified on the board. But Magnum Sal is more traditionally player-turn oriented (doing 2 actions each time it's your turn, not claiming actions to perform in a later round).
Caylus has the concept of building buildings which can then receive workers in later placement phases (giving a benefit to the player who build them). You don't build building in Magnum Sal; there are a few fixed buildings printed on the board (and a concept of placing a worker on one to get a benefit if it's used - but that worker leaves at the end of the round).
Magnum Sal has "tactical maneuvering on the mine map" elements which have nothing similar in Caylus.
And as you say, Magnum Sal indeed has some randomness which Caylus doesn't.
(I was a rules translator for Magnum Sal and have played it once and have played Caylus a couple dozen times.)