Terms aggregation on both axes of line graph and dot size using doc count

I have documents like this
{
"_index": "bbd-smartaccess",
"_type": "transaction",
"_id": "361989",
"_version": 1,
"_score": null,
"_source": {
"transaction_id": 361989,
"@timestamp": "2019-08-12T10:23:41.154Z",
"lastname": "Sen",
"firstname": "Ajay",
"employeecode": "001",
"cardholder": "Ajay Sen (0003202870)",
"transactiontime": "2019-08-09T10:17:25.000Z",
"transactiontype": "OFFICE_OUT",
"cardno": "0003202870",
"@version": "1"
},
"fields": {
"time_of_day": [
"15:47"
],
"@timestamp": [
"2019-08-12T10:23:41.154Z"
],
"transactiontime": [
"2019-08-09T10:17:25.000Z"
],
"slot_of_day": [
"15-Q2"
],
"day_of_week": [
"#5 Friday"
]
},
"sort": [
1565605421154
]
}

I want to visualize a scatter plot with day_of_week on y-axis, slot_of_day on x-axis and dot size representing the doc count.

I am trying to use line graph for this (with line option off). I am able to plot slot_of_day on x-axis and dot size representing the doc count, but can't see any option to plot day_of_week on y-axis. Y-axis seems to accept only numeric data.

Can someone suggest me a way to achieve this?

Kibana visualizations don't currently support scatter plots with unaggregated data. You might be able to accomplish what you're hoping inside of Canvas, however.