I found a source that helped with converting 40 yard dash times into Madden speed ratings:
Kalon Barnes (CB): 99.
Travon Walker (DE): 89-90.
Aidan Hutchinson (DE): 81.
Sauce Gardner (CB): 92-93.
Kavyon Thibodeaux (DE): 86.
Garrett Wilson (WR): 94.
Chris Olave (WR): 93.
Skyy Moore (WR): 92-93. Jahan Dotson (WR): 92.
George Pickens (WR): 90-91.
Desmond Ridder (QB): 89.
Kenny Pickett (QB): 81-82.
Kenneth Walker III (RB): 94.
Breece Hall (RB): 93.
Zamir White (RB): 93.
James Cook (RB): 92.
Dameon Pierce (RB): 86.
Greg Dulcich (TE): 83.
Devonte Wyatt (DT): 80.
Jordan Davis (DT): 80.
Troy Andersen (LB): 92.
Channing Tindall (LB): 90-91.
Tariq Woolen (CB): 98-99.
Kaiir Elam (CB): 93.
Trent McDuffie (CB): 91.
Roger McCreary (CB): 89-90.
Lewis Cine (S): 94.
Daxton Hill (S): 94.
Jaquan Brisker (S): 90.
Kyle Hamilton (S): 87.
Jake Camarda (P): 87.
Matt Araiza (P): 83.