You're looking for "send to many", it's under the Electrum Tools menu.
Example: see
DarkStar_'s ChipMixer spreadsheet:
36pmEH2TKXUo2C4hbzxQTiGGy5jrotZ599 , 0.0345
bc1q45n2uvxt3h9ta5zfnhtfcslgeyv5rk9qt7fav6 , 0.0375
bc1qptg5vvtmwwgn96qgwgalpflqjvxxmvlwmu8529 , 0.021
32sMPM7zWfsAUPywteMcraesjEK5WkMFbc , 0.0225
bc1qgx2ld7amg5p6ytf5dh3snwrz5apcvaaegq30mr , 0.00675
1G9KcU1snXzh9UW4M7E1xVqfDyPfC2ELDU , 0.00375
33jr6swgJxHwyFTgXKcv7kbKSy4du8Yt8r , 0.0045
bc1qlyfk8qsz258rmjrj7wezgsa9qf7d0mveeelzr7 , 0.03525
bc1qgnn4z0kk48tz2p49r8sakk9uvdn063cywde7nz , 0.0345
3N2E8VoHyK6Ux2ummEC2Yp5stfdptvMASB , 0.0375
3987TtXJUiwqWPT3qGXwHvEvVrEeoA1vCd , 0.01125
36w3p7Ms773anDiLWxdQPfS8zC5R8hGVbL , 0.036
bc1qxw7gmjzf5neuuryugqd03sc4k863ad3unsdk53 , 0.02025
bc1qmstu82u22rhf5carza9052skyr8ar83c4f4g3e , 0.033