It's not possible to use the Excel import for data in this format. I recommend to transform it into yEd's Edge List format instead, in which each line explicitly specifies the source and target node of an edge.
For your example, it would look like this (the ordering of the lines doesn't matter, commas separate table cells):
MANAGER, SUPERVISOR 1
SUPERVISOR 1, WORKER 1
SUPERVISOR 1, WORKER 2
SUPERVISOR 1, WORKER 3
MANAGER, SUPERVISOR 2
SUPERVISOR 2, WORKER 4
...
MANAGER, SUPERVISOR 3
...